Composite back-up ring structure



United States Patent 3,158,378 0lt iPt3 SHE BACK-U? RING STRUCTURE GlennL. Leomis, R0. Box 728, Pasadena, Tex. Filed Feb. '2, 1962, er. No.179,538 Claims. (til. 277-198) The present invention relates to apacking structure for use in forming a seal between a rod-like elementand a surrounding wml of a well pipe or the like and, more particularly,to a packing structure incorporating an improved composite back-up ringfor preventing cold end flow of a packer when the packer is set againstthe wall of a well pipe and then subjected to high internal pressures.

The packing structures of the present invention is preferably intendedfor use in a device for testing well pipe or the like for leaks, but itmay also be used with other well equipment when it is desired to set apacker in the Well pipe and the packer is subsequently subjected toextreme pressures. A typical testing device for which the packingstructure of the present invention is preferably used is disclosed in mycopending United States application Serial No. 170,711, filed February2, 1962, and entitled Testing Tool for Well Pipe or the Like and filedconcurrently herewith. The subject matter of the testing tool disclosedin the aforementioned copending application is incorporated by referenceherein for that purpose.

In recent years, the flow tubing for oil or gas wells or the like hasbeen made with an internal plastic lining. The plastic lining which isusually coated on the interior of the pipe provides protection to themetal pipe from the corrosive action caused by acids and other fluidsflowed therethrough; The plastic lining of the sections of pipe is quitefragile and may be easily damaged if contacted by a well tool having aharder surface than the lining. In my aforementioned copendingapplication, there is dis closed completely a well tool suitably coatedon its ex terior surfaces with a material as soft as or softer than thelining so as to protect the lining as the well tool is inserted into thepipe.

The back-up rings heretofore used in association with resilient packersto prevent cold flow of the packer under extreme pressure conditionshave been made from arcuate metallic segments which were simultaneouslyexpanded into engagement with the wall of the pipe when the packer wasexpanded. Such a back-up ring is disclosed in my copending applicationSerial Number 754,197, now Patent No. 3,038,542, filed August 11, 1958,and entitled Tester Apparatus for Oil Wells or the Like. It has beenfound that the engagement of the metallic segments of the expansiblesegmental back-up ring with the plastic lining when the same areexpanded by the annular pressure exerted by the packer immediatelycrushes the lining in the pipe and thus, when the well tool is removed,the effectiveness of the lining has been materially reduced as the pipecan be subjected to corrosive action at this point.

An important object of the present invention is to provide a packerback-up ring structure comprising an expansible segmental back-up ringcomposed of arcuate metallic segments having a covering of non-metallicmaterial on their outer peripheral surface.

Another object of the present invention is to provide an expansiblepacker back-up ring having outer peripheral surfaces made from anon-metallic material which will not damage the plastic lining of a wellpipe when engag ing the same, the back-up ring being providedwitharcuate metal segments for sustainingthe thrust exerted by the packerswhen the packers are caused to cold flow by application of extremepressures thereto.

Ancillary to the preceding object, it is a further object of the presentinvention to provide an expansible packer back-up ring comprised ofouter arcuate non-metallic ele- 3,158,378 Patented Nov. 24, 1964 mentsfor engaging well pipe wall and inner metallic segments fixed thereto,the metallic segments sustaining the forces necessary to cause expansionof the ring.

Still another object of the present invention is to pro vide anexpansible packer back-up ring comprised of a plurality of metallicsegments having replaceable nonmetmlic coverings over their outerperipheral surfaces.

Sections of well pipe are now made with threaded male and female endswhich are thickened over the normal wall thickness. By providing such anarrangement, it is no longer necessary to use a collar in attaching twosections of well pipe together. However, the newly designed well pipewith the thickened end portions have a decreased internal diameter attheir point of connection due to the internal upset caused by its maleand female ends. Consequently, in order that well tools utilizingpackers may pass through the internal upset, the well tools must be madeof a decreased diameter and thus the packer backup rings have to becapable of accommodating a greater expansion tolerance than heretoforenecessary.

Ancillary to the above, it is another important object of the presentinvention to prouide an expansible segmental back-up ring capable ofhaving a greater tolerance of expansion than heretofore realized andthen returned to its original retracted position.

The foregoing and other objects and advantages of the present inventionwill appear more fully in the following specification, claims anddrawings in which:

FIGURE 1 is a fragmentary vertical section through a portion of wellpipe and illustrating the packing structure of the present inventionutilized on a testing device being lowered into the well pipe, thetesting device being shown partly in section and partly in elevation;

FIGURE 2 is a view similar to FIGURE 1 but illustrat- I being shown inelevation and the well pipe being omitted for the purpose of clarity;

FIGURE 4 is a perspective view having a portion broken away andillustrating the expansible packer backup ring of the present invention;and

FIGURE 5 is a fragmentary longitudinal sectional view through a modifiedform of expansible packer back-up ring.

Referring now to the drawings wherein like character and referencenumerals represent like or similar parts, the packer back-up ringstructure of the present invention is illustrated utilized on the lowerend of a testing device generally designated by the numeral 1%. Thetesting device 16 is of the type disclosed in my aforementioned pendingapplications and generally includes an elongated tester body havingspaced packers mounted thereon and adapted to be expanded intoengagement with the walls of a well pipe 12 or the like. The testingdevice it) is provided with suitable fluid passages for supplyinghydraulic fluid under pressure to pistons acting against the packers,the pistons compressing the packers longitudinally and thus expandingthem transversely so that they form sealing engagement with the wellpipe 12 todefine a sealed. off section of well pipe to be tested.

The testing tool 10 is also provided with suit-able pres-- of Well pipeor' the well pipe wall itself may be tested by such a fluid pressuremethod. After the well pipe has been tested, the pressure on thehydraulic fluid in the testing tool is relieved and the packers arerelaxed so in the well pipe to provide for a subsequent test. The

testing procedure briefly described above is disclosed in detail in myaforementioned pending application entitled Testing Tool for Well Pipeor the Like as well as in my prior United States Patent No. 2,731,827,issued 3 an. 24, 1956.

Referring now in detail to FIGURES l and 2, the well pipe 12; is of thetype having a protective lining C made of a plastic material such as anepoxy resin or the like. The packing structure of the present inventiongenerally designated by the numeral 14 is carried on the elongated bodyof the testing device ll) which may be considered for the purposes ofthis description as a rod-like element 16. Packing structure 14-includes a substantially cylindrical resilient packer 18 made of anelastomeric material such as iubber, synthetic rubber or the like, apiston element 20 and a back-up ring structure 22. The piston 20 abutsone end of the packer and may be moved longitudinally toward the packerby application of hydraulic fluid under pressure to the interior of thesame. The rod-like element 16 is provided with an abutment portion ornose end 24 and the back-up ring structure 22 is interposed between theabutment portion 24 and the end of the packer l8 opposite the endabutting the piston 2 It will now be understood that when the piston 29is extended or moved downwardly from the position 05' FIGURE 1 to theposition of FIGURE 2, the packer 18 is compressed longitudinally againstthe back-up ring structure 22 and simultaneously expanded transverselyinto sealing engagement with the wall of the flow tubing 01 well pipe12.

Since the resilient packer 18 is made of an elastomeric material, itwill not damage the plastic lining C of the well pipe when it engagesthe same. As shown in FI URES l and 2, the exposed portions of thetesting evice including the piston 2t and the rod-like element in withits abutment portion 24 are coated with a non-metallic material M assoft as or softer than the plastic lining C of the pipe. This feature ofthe well tool is disclosed in detail in my aforementioned applicationentitled Testing Tool for Well Pipe or the Like.

The back-up ring structure 22 includes an expansible segmental back-upring 26 positioned intermediate a pair at 34. The expansible segmentalring 26 has each of its ends provided with an annular invertedcone-shaped surface 36 which cooperate with and are complementary to thecone-shaped surfaces 34 of ring elements '23 and 39. It will now beapparent that when the piston 29 moves downwardly from the positionshown in FIGURE 1, it

is effectively working against the abutment portion 24 in that itcompresses the packer l8 and causes the same to expand transversely, thepacker in turn pushing the ring element 2%; toward the ring element 30.A wedging action occurs as the cone surfaces 34 of ring elements 28 and3d push against the inverted cone surfaces 36 of the segmental back-upring 26, thus causing uniform expansion of the back-up ring 26 radiallyoutwardlyuntil it engages the wall of the well pipe 12, as shown in FIG-URE 2. When the back-up ring 26 is expanded, it prevents longitudinalextrusion of the packerwhen the packer is subjected to extremepressures.

The expansible segmental back-up ring 26 is composed of a plurality ofarcuate metallic segments 33 retained in .a retracted position by a pairof endless elastomeric retaining bands 40 and 42 and a plurality ofnon-metallic arc'uate covering elements 44, each being secured to one ofthe segments 38 by means of a brass screw 46. In-

part of the cone-shaped surface 36 of the ring. Further,

the segments 38 are provided on their outer curved periph- I eralsurface 52; with spaced annular undercut shoulders 43 and a pair ofcircumferentia-lly extending grooves 56). The grooves 50 receive theO-ring retaining bands 40 and and maintain them in longitudinal spacedrelationship I which are received in the undercut shoulders 48 of themetallic segments 38 when the non-metallic elements 44 are fixedlysecured thereto. By such an arrangement, the thrust exerted on the endof the expansible packing ring by the cold flow of the packer istransferred to and sustained by the metallic segments 33 rather thanentirely by the covering element 44. 7

It will be noted from FIGURE 4 that the ends of each of the non-metallicelements 34 are tapered inwardly, as indicated at 36", and thus when theelements 44 are assembled on the arcuate metallic segments 38 they forma continuation of the tapered surfaces 36' to define the invertedconical-shaped end surfaces 36.

Each of the non-metallic covering elements 44 is fixedly secured to oneof the metallic segments 33 by the brass screw 46. The brass screw 4-6has its head countersunk below the peripheral curved surface 52 of theelement 44 so that it will not contact the wall of the well pipe whenthe ring is expanded. By utilizing a screw to attach the non-metallicelements 44 to the arcuate segments 38, the non-metallic elements 44 maybe replaced when they become worn or damaged.

The non-metallic elements 44 are preferably made from a resinimpregnated fiber such as phenolic impregnated Fiberglas or the like.However, they may be made from an elastomeric material such as rubber,synthetic rubber or the like or they may be made from a plastic materialsuch as'polyurethane. By providing covering elements 44 for each of thearcuate segments 38, it will now be appreciated that when the back-upring is expanded and contacts the wall of the Well pipe 12, it will notthan age the lining or coating C. Also, by providing elastomeric endlessretainer bands 40 and .42, circumscribing the metallic segments 38 andinterposed between the same and the non-metallic covering elements 44,the expansible ring can be expanded from its retracted position agreater distance than previous back-up rings utilizingsnap rings or coilsprings. Interposing the retaining bands 40 and 42 between the metallicsegments and the non-metallic segments 44 protects the bands fromexposure to fluids within the well as well as providing a simple meansof assembling the ring 26 as a unit. Further, utilization of wedgingmeans, such as the rings 28 and 30 on both ends of the ring 26, providesfor a greater expansion tolerance which will be uniform over the entirerange of expansion.

FIGURE 5 illustrates a slight modification of the backup ring of thepresent invention in that the metallic segments 33 are provided with asingle enlarged groove 50 which receives aresilient endless retainerband 40' that is rectangular in cross-section. In this modification ofthe invention, the screw 46 extends through the outer covering element44 and an aperture 4%)" provided in the band 40', the screw beingthreaded into the metallic segment 38'.

i Although the metallic segments 38 and the non-metallic coveringelements 44 have been illustrated in simple arcuate form whereby theyabut on their respective radial faces, 'it will be understood by'thoseskilled in'the' art, the expansible back-up ring of the presentinvention may incorporate the overlapping feature of the segmentsdisclosed in the back-up ring of my copending application SeriallyNumbered 754,197 without departing from the spirit of the presentinvention. a

While the invention has been primarily disclosed in relation to itspreferred use with a packing structure of a testing tool for oil and gaswell flow tubing, it is, of course, within the scope of the presentinvention that the improved expansible back-up ring could be used with apacker in flow tubing or casing whenever it is desired to form a sealbetween any rod-like element of a well tube and the wall of the tubingor casing. Therefore, the terminology used in this specification is forthe purpose of description and not for limitation as the scope of theinvention is defined in the claims.

What is claimed is:

1. A composite expansible back-up ring for use with a resilient packerset in a plastic lined well pipe or the like, said back-up ringcomprising: a plurality of arcuate metalllc segments; a plurality ofnon-metallic arcuate shaped elements, each of said non-metallic elementscovering the entire exterior surface of each of said metallic segments;means for attaching each of said non-metallic elements to one of saidmetallic segments; and resilient means circumscribing said arcuatemetallic segments and interposed between the same and said non-metallicarcuateshaped elements for retaining them in a retracted position as aunit.

2. The composite expansible back-up ring of claim 1 wherein each of saidnon-metallic arcuate shaped elements is made from a resin impregnatedfabric.

3. The composite expansible back-up ring of claim 1 wherein each of saidnon-metallic arcuate shaped elements is made of an elastomeric material.

4. The composite expansible back-up ring of claim 1 wherein each of saidnon-metallic arcuate shaped elements is made of a plastic material.

5. The composite expansible back-up ring of claim 1 wherein saidresilient means circumscribing said segments is an endless retainer bandmade of an elastomeric material.

6. The composite expansible back-up ring of claim 1 wherein said meansfor attaching each of said non-metallic elements to said metallicelements includes at least one screw extending inwardly through one ofthe non-metallic elements and threaded into one of the metallicsegments,

each screw having its head countersunk below the exterior peripheralsurface of the non-metallic elements.

7. A composite expansible back-up ring for use with a resilient packerset in a plastic lined well pipe or the like, said back-up ringcomprising: a plurality of arcuate metallic segments; meanscircumscribing said segments for retaining them in a retracted positionas a unit; said means including at least one groove in the exteriorperipheral surface of each of said segments, the grooves in each of saidsegments defining an annular peripheral groove about the segments whenthe segments are arranged as a unit and at least one resilient retainerband carried in the annular peripheral groove; and a plurality ofarcuate shaped non-metallic covering elements, each of said coveringelements being fixedly secured to the exterior peripheral surface andentirely covering the exterior peripheral surface of one of saidmetallic segments, said band being interposed entirely between themetallic segments and the non-metallic covering elements when the sameare retracted as a unit.

8. The composite expansible back-up ring of claim 7 wherein saidresilient retainer band is rectangular in cros -section and wherein eachof said non-metallic covering elements are fixedly secured to therespective metallic segments by at least one screw extending through theelement and the band and threaded into the respective metallic segment,the screw having its head countersunk beneath the exterior surface ofthe non-metallic element.

9. The composite expansible back-up ring of claim 7 wherein oppositeends of the back-up ring defined by the arcuate metallic segments andarcuate shaped nonmetallic covering elements are each tapered to provideinverted conical surfaces.

10. A composite back-up ring of claim 7 wherein said resilient retainerband is an O-ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,536,025 Lamb et al. Apr. 28, 1925 1,861,614 Schweitzer June 7, 19322,555,647 King June 5, 1951

1. A COMPOSITE EXPANSIBLE BACK-UP RINGFOR USE WITH A RESILIENT PACKERSET IN A PLASTIC LINED WELL PIPE OR THE LIKE, SAID BACK-UP RINGCOMPRISING: A PLURALITY OF ARCUATE METALLIC SEGMENTS; A PLURALITY OFNON-METALLIC ARCUATE SHAPED ELEMENTS, EACH OF SAID NON-METALLIC ELEMENTSCOVERING THE ENTIRE EXTERIOR SURFACE OF EACH OF SAID METALLIC SEGMENTS;MEANS FOR ATTACHING EACH OF SAID NON-METALLIC ELEMENTS TO ONE OF SAIDMETALLIC SEGMENTS; AND RESILIENT MEANS CIRCUMSCRIBING SAID ARCUATEMETALLIC SEGMENTS AND INTERPOSED BETWEEN THE SAME AND SAID NON-METALLICARCUATESHAPED ELEMENTS FOR RETAINING THEM IN A RETRACTED POSITION AS AUNIT.